Remote control of implantable device through medical implant communication service band

ABSTRACT

A system and method for communicating data and signals through the Medical Implant Communication Service Band using a repeater or base station in the proximity to an implantable device within a patient is disclosed. In a preferred embodiment, the device is capable for early detection and monitoring of congestive heart failure in a patient. Impedance measurements, or other health parameters depending on the type of implantable device or sensor used, are sent using a bi-directional low-power radio operating in the MICS band to a nearby base station which may provide signal processing and analysis. The base station may have an interface to one or more communications networks to connect to a remote location. The system and method of the present invention permits a healthcare professional to monitor an ambulatory patient&#39;s condition at a remote location and to program the implanted device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/622,184, filed Jul. 16, 2003, which is acontinuation-in-part of U.S. patent application Ser. No. 10/155,771,filed May 25, 2002, claiming priority of the German Patent Serial No.101 48 440.2, filed Oct. 1, 2001. These applications are herebyincorporated by reference in their entireties, and priority is claimedto them.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to electronic medical devices that are implantedin the body of a patient. More particularly, it relates to a congestiveheart failure monitor for detecting and monitoring the progression ofcongestive heart failure and the method of remote control andcommunication with the device.

2. Description of the Related Art

Many patients who have suffered one or more myocardial infarctionssubsequently require treatment for congestive heart failure (CHF). Theleft heart fails while the pumping function of the right heart remainsadequate, because the latter has only about 20% of the workload of theformer. This leads to an increase in blood volume congested to thelungs, resulting in pulmonary congestion, build up of increased levelsof fluid, and congestion of internal organs including the stomach andintestines. Increased fluid in the stomach and intestines reduce theirability to absorb drugs prescribed for treatment of CHF, particularlydiuretics. The congestion is often accompanied by a worsening ofmyocardial function, with consequent drop in blood pressure and reducedrenal perfusion, which only further aggravates the congestive situation.Thus, late recognition of congestion leads to increased dosages of oraldiuretics that are unsuccessful to treat the condition, ultimatelyrequiring that the patient be hospitalized.

Avoidance of hospitalization and the pitfalls of late treatment requiredetection of CHF at an early stage, so that the prescribed drugs can befully absorbed and effective. If detected early, a combination ofdiuretics and other drugs can slow the progress of the disease and allowthe patient to enjoy an improved lifestyle.

An extensive review of telemonitoring for the management of heartfailure by Louis et al. has been published in the past in the EuropeanJournal of Heart Failure. The conclusion of this article is thattelemonitoring might have an important role as a strategy for deliveryof effective health care for patients with heart failure. However, thecurrent state of the art still lacks an adequate means to monitor thedata and to communicate data.

The ApexPro FH enhances patient safety by using a bi-directional,frequency-hopping infrastructure to help ensure that patient data istransmitted clearly and completely to a central patient monitoringstation. While this system is based on external data and provided by GEHealthcare using a Unity Network, the use of the medical implantcommunication service band is not part of the system nor is animplantable device considered to be part of the communication system.This system relies rather on data external to the patient.

Several patents have looked into impedance monitoring and dataprocessing and monitoring and diagnosing hypertension or congestiveheart failure in patients. Among those is Riff, U.S. Pat. No. 5,876,353which describes an Impedance Monitor for Discerning Edema throughEvaluation of Respiratory Rate. U.S. Pat. No. 5,957,861, Combs et al.and its continuation, U.S. Pat. No. 6,512,949 describes an ImplantableMedical Device for Measuring Time Varying Physiologic ConditionsEspecially Edema and for Responding Thereto. The U.S. Pat. No.6,104,949, Pitts Crick et al. relates to a device and method used forthe diagnosis and treatment of congestive heart failure. Specifically,this invention senses a trans-thoracic impedance as well as patientposture and correlates changes in posture with trans-thoracic impedancein order to assess the degree of congestive heart failure. The Devicefor Detecting Pericardial Effusion, Godie et al., U.S. Pat. No.6,351,667 describes an apparatus for detecting pericardial effusion thatincludes a measurement apparatus connected to a wire probe to beanchored to the right heart ventricle and two other wire probes tomeasure the impedance between different probes in order to assess thedegree of pericardial effusion. U.S. Pat. No. 4,899,758, Finkelstein etal., describes a Method and Apparatus for Monitoring and DiagnosingHypertension and Congestive Heart Failure, by using C2 and brachialartery pulses to discriminate a threshold of certain Windkesselfunction. U.S. Pat. No. 6,336,903, Bardy et al. relates to an automaticsystem and method for diagnosing and monitoring congestive heart failureand outcomes thereof. A plurality of monitoring sets are retrieved froma database and each patient's status change is tested against anindicator threshold corresponding to the same type of patientinformation as the recorded measures to which it was compared. Theindicated threshold corresponds to a quantifiable physiological measureof a pathophysiology indicative of congestive heart failure. U.S. Pat.No. 6,416,471, Kumar et al., describes a Portable Remote PatientTelemonitoring System. This invention has useful application to theconnection of patient data during drug trials and medical testing forregulatory approvals as well as the management of patients with chronicdisease. U.S. Patent Publication No. 2002/0115939, Mulligan et al.describes an Implantable Medical Device for Monitoring Congestive HeartFailure in which incremental changes in a parameter data over timeprovide insight into the heart failure state of the patient's heart.

None of those previous disclosures however describes adequate means tocommunicate those signals in a safe way between an implant device and anexternal data handling and coordinating center.

It is a principal aim of the present invention to provide an implantableheart failure monitor which is capable of achieving very early detectionof CHF. It is a further aim of the present invention to describe themethod of remote controlling an implanted diagnostic or therapeuticelectronic device in uni- or bi-directional ways.

SUMMARY OF THE INVENTION

The implantable medical device of the present invention may be of sizesmaller than a typical pacemaker device—about the size of a thumb. Itmay be implanted in a subcutaneous pocket formed by a surgeon in thepatient's chest, under local anesthesia and minimally invasiverequirements. The device includes a hermetically sealed can withappropriate electronic circuitry inside. A set of device-mountedelectrodes may be used to measure the impedance of the adjacent tissueand most especially the lung tissue. The progressive retention of fluidin the lungs and congestion of the ventricle together result in areduced resistance measurement that is monitored either continuously orperiodically by the device.

In a preferred mode of operation, the device alerts the patient and/orthe attending physician when a diagnostic threshold is reached which isindicative of the progression of CHF. The overall architecture of thedevice follows implantable practice, however, it should be appreciatedthat the partitioning of the device is flexible and the division ofsensing and analysis structures can be shared between implanted andexternal (remote, i.e., non-implanted) devices. A low-power radiotransceiver operating in the Medical Implant Communications Service(MICS) band can be use for linking the device to a proximate basestation. The base station can communicate with one or more remotelocations via telecommunications or wideband networks to permitmonitoring patient data and programming the device remotely.

The Medical Implant Communications Service is an ultra-low power,unlicensed, mobile radio service for transmitting data in support ofdiagnostic or therapeutic functions associated with implanted medicaldevices. The MICS permits individuals and medical practitioners toutilize ultra-low power medical implant devices, such as CHF monitors,cardiac pacemakers and defibrillators, without causing interference toother users of the electromagnetic radio spectrum. No licensing isrequired, but MICS equipment is intended for operation only byhealthcare professionals.

Signal processing may be performed entirely internally within thedevice, or the device may operate as a data logger and communicate withan external base station which participates in data reduction andanalysis.

Although specific structures are shown as being dedicated to specifictasks, it should be apparent that certain functions may be shared if thedevice is integrated with other diagnostic or therapeutic devices. Forexample, the electrode set used to determine the impedance of the lungscould be used for additional purposes.

It is an object of the present invention to provide a device-implementedmethod of detecting and monitoring congestive heart failure in a patientwherein the body portion encompasses the patient's heart, includingperforming impedance measurements by means of a signal injected into thebody portion from the device and retrieved as a signal subdivided into acardiac portion, a pulmonary portion, and a total impedance portion.

It is a further object of the present invention to provide a method ofremote control of an implantable device through the Medical ImplantCommunication Service band by changing the settings, function,characteristics or parameters of the implantable device viabi-directional communication through the MICS band of 402 to 405 MHz.

It is a further object of the present invention to provide a method ofremote control using a local repeater base station that communicatesbi-directionally and transmits signal to the implant device on one endand communicates and transmits the signal through a telephone land line,wireless telephone, or through a network such as the Internet to acontrol station on the other end.

It is a further object of the present invention to provide a patientmonitoring system with an implantable device wherein the implantabledevice is one of a congestive heart failure monitoring device, a cardiacpacemaker, defibrillator, neurostimulator, muscle stimulator, gastricstimulator, or diagnostic implantable device for monitoring a variety ofphysiologic body functions such as CO₂, blood pressure, oxygen, glucose,ventilation, heart rate, activity, posture, hormones, cytokines, orneurofunctions.

It is a further object of the present invention to provide a system forremote control of an implantable device through the Medical ImplantCommunication Service band capable of changing the settings, functions,characteristics or parameters of an implantable device viabi-directional communication through the MICS band of 402 to 405 MHz.

It is a further object of the present invention to provide a method ofcommunicating data with an implantable device through Medical ImplantCommunication Service band using a repeater in proximity to the patient.

It is a further object of the present invention to provide a method ofcommunicating data using a local repeater in proximity to a patientcapable of communicating bi-directionally that communicates with theimplantable device on one end and translates or amplifies the signalswith a data handling and coordinating center on the other hand throughan Internet or wireless Internet connection.

It is a further object of the present invention to provide a method ofcommunicating patient-derived data originating from an implantabledevice between a data handling and coordinating center and a localpatient care physician center.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aims, objectives, aspects, features and attendantadvantages of the invention will be further understood from a reading ofthe following detailed description of the best mode presentlycontemplated for practicing the invention, taken with reference tocertain presently preferred implementations and methods, and inconjunction with the accompanying drawings, in which:

FIG. 1 is an exterior view of an embodiment of the device;

FIG. 2 is a schematic representation of an implantation of the device inthe body of a patient;

FIG. 3 is a block diagram of the internal circuitry of the device;

FIG. 4 is a flow chart illustrating the operation of the device;

FIG. 5 is a graph of the device operation in terms of the reciprocal ofimpedance versus time;

FIG. 6 is a schematic drawing of a system comprising an implanted devicein a patient's body and a proximate base station having links to varioustelecommunication facilities;

FIG. 7A is a block diagram of one embodiment of a base station accordingto the present invention;

FIG. 7B is a block diagram of an alternative embodiment having adedicated microcontroller integrating the functions of 210, 211, 212,and 213 in FIG. 8;

FIG. 8 is a block diagram of system operation through a base/repeaterstation, a data handling and coordinating center and a local patientcare physician center;

FIG. 9 is a block diagram of another exemplary embodiment of theinvention;

FIG. 10 illustrates the advanced processing and analysis of informationderived from patients' history, physical examination, currentmedication, patient related parameters and the actual and/or previousdata received from a patient implant device such as a heart failuremonitor, ECG monitor, activity sensor, pacemaker, defibrillator or otherdiagnostic or therapeutic electronic implant in the patient's body. Thedata from the implant device may be analyzed, evaluated and/or commentedin light of evidence-based medicine by using input from the library withmedical publications, drug action and adverse effects, medicalguidelines in order to provide a specific patient tailoredrecommendation.

DETAILED DESCRIPTION

The device of the preferred embodiment of the invention is disclosed inthe preferred implementation as being a stand-alone diagnostic device tosimplify the description of its operation. Throughout the several viewsof the drawings identical reference numerals indicate identicalstructure. Views of the device either alone or as implanted are notintended to represent actual or relative sizes.

FIG. 1 illustrates the exterior of the device 18 in its presentlypreferred embodiment. Device 18 includes a circuit module (to bediscussed below in conjunction with the description of FIG. 3) within ahermetically sealed “can” or case 24 composed, for example, of titanium.The size of the case 24 is clearly dictated by the size of the internalcircuit components and wiring included printed circuit board(s) andother forms, but preferably is very small, currently about 5.0 cm longby 2.0 cm wide by less than 1.0 cm thick.

Case 24 is a standard rectangular case with rounded edges and a headerof epoxy resin on top (not shown in FIG. 1). In one preferredembodiment, Case 24 has a curvilinear shape which presents a concaveshape or surface 26 on one side (in contrast to an edge of the case) anda convex shape on the opposite side of the case. Four surface mountedelectrodes 10, 12, 14 and 16 are positioned in spaced-apart relationshipon the slightly concave surface 26, with each electrode beingelectrically insulated from the case 24 itself. The electrodes should beof low polarization, preferably composed of or coated with iridiumoxide. By way of example, “inner” electrodes 10 and 12 are spaced aparton the concave side inward of opposite edges and centrally along thelength of the case, while “outer” electrodes 14 and 16 are spacedfarther apart—preferably, by at least about 4 cm—on that same sideinward of opposite edges and centrally along the width of the case. Theshape of the case is designed (and preferred) to conform to the shape ofthe anatomy of the human chest. With the concave side of the case placedtoward the interior of the body within the implant site of device 18,the device is prevented from turning within its subcutaneous pocketwhich would otherwise position the surface electrodes at the wrongside—namely, toward the exterior of the patient's body. The reason forthis positioning will become apparent as the description proceeds.

The most preferred implant site of the device is the left lower anteriorlateral hemithorax of the patient's body as shown in FIG. 2. In part,this is because optimal sensing occurs with the device placed slightlyto the left of the patient's midline. FIG. 2 illustrates in schematicform a side view of a patient (in phantom) with the device 18 implantedin a pectoral of the chest over the basal region of lungs 28 and heart30, outside the rib cage 32. An implantation at the preferred siteplaces the device on the left anterior thorax side between the 5th and6th intercostals space. In this position of the device, an impedancesignal is developed which represents the impedance of the lungs andheart tissue by virtue of current injected into the circuit path thatestablishes a field through that portion of the body from device 18.

FIG. 3 illustrates the exemplary circuit module within device 18. Animpedance signal generator 40 injects signal current into the body,preferably through “inner” electrodes 10 and 12. The current traversesthe circuit path through the body portion of interest and has a returnpath through “outer” electrodes 14 and 16. Field lines 38 (FIG. 2)attributable to current flowing from the electrodes emanate from theconcave side 26 of device 18, and, together with the electrode spacing,define the “viewing volume” of the device for the impedance sensingcircuitry. Electrode spacing of at least four cm between the outerelectrodes 14, 16 will allow a measurement to a depth of up to 10 cm oflung tissue in the anterior lateral lower left thorax. The field linesproduced by current through the circuit path intersect the lung tissue28 and are somewhat less influenced by the volume of the heart 30.

The circuit module within device 18 is powered by a preferablylithium-ion battery 50. Impedance generator 40 is controlled bymicroprocessor 48, as is logic 42 for analysis and memory 44 for data.Measured values of impedance are stored in memory 44, and used bymicroprocessor 48 to calculate various functions of the measuredimpedance values. A threshold detector 46 may be incorporated in device18 as a patient alert function or alarm (e.g., by emitting an acousticsignal, vibrations, or low level pulses for local muscle contractions,recognizable by the patient) indicative of a need for immediateintervention when impedance associated with fluid level 64, for example,is detected. Such an alarm condition may also be signaled by telemetryfrom an antenna or coil 58 within the circuit module at themicroprocessor, normally used to transmit the other impedance data, to aremote programmer 56 to monitor and log the progress of the disease andthe therapeutic effect of treatment for review by the patient'sphysician.

In a preferred embodiment, the device is adapted to monitor impedance ata digital rate of 128 Hz, for partitioned analysis of contractilecardiac function, pulmonary ventilation function and long term pulmonaryimpedance, over an average of 72 hours or more. Signal processing allowsdeviation from basic impedance of the body region of interest,especially the lungs, to be detected as an early monitoring of adecrease in lung impedance, indicative of increasing congestion by fluidcontent in the lungs. The decrease in lung impedance associated with CHFoccurs as the lungs fill with fluid, which is a considerably betterelectrical conductor than the normal lung tissue. Exemplary values ofimpedance for lung tissue are 400-1,000 ohms per centimeter (Ω/cm),compared with 50 Ω/cm for fluid.

Representative fluid levels accumulated in the lungs are illustrated inFIG. 2 at 60, 62 and 64. Level 60 represents the relative additionalamount of fluid associated with normal lung function. Level 62represents the relative amount of fluid present for a compromised lungfunction associated with CHF. And level 64 is the relative stilladditional amount of fluid associated with severely reduced lungfunction requiring immediate attention, indicative of advanced CHF.

The device 18 may be designed to provide a threshold or trigger level atan accumulation of fluid corresponding approximately to level 64.Algorithms are used to convert real time measurements into a diagnosticindication of congestion. The device may be operated continuously andthe impedance data are then analyzed in kind. ECG data may be usedadditionally, detected at the outer electrodes 14 and 16 to improve thecapability of the device to discern impedance changes in the heart.

FIG. 4 is a flow chart of an exemplary detection algorithm used by thedevice 18. On commencement, counters are initialized and impedancegenerator 40 is turned on to inject signal current into the body via theinner pair of electrodes 10, 12 (start, 70). The impedance signalcurrent is preferably a rectangular biphasic pulse wave at a rate of 128Hz and a peak-to-peak amplitude of 1 milliampere (ma), or,alternatively, an alternating current in a range from 5 microamperes(μa) to 10 μa. The pulses may be injected with considerably higherenergy content than the AC wave because of their very short duration(e.g., 15 μsec or less), with no risk of myocardial depolarization, andare capable of detecting cardiac changes as well as pulmonary changes.

Impedance is then calculated (72) from a measurement of the resultingvoltage at the outer pair of electrodes 14, 16. Alternatively, a fixedvoltage may be applied across the excitation (inner) electrodes and theresulting current measured at the measurement (outer) electrodesreflects the impedance. A long-term average of the impedance value iscomputed (74), covering a period ranging from days to weeks as a runningaverage. A short-term average of the impedance value is also computed(76), covering a period from hours to days. The difference between thelong-term (LT) and short-term (ST) averages is calculated (78) as aslope measurement (V) indicative of deterioration of the lung condition,to detect accelerating lung congestion. If the value V exceeds apredetermined threshold (slope) value (80), an alarm condition isindicated and the patient alert function (46, FIG. 3) is initiated. Ineither case (an alarm condition or not), another impedance measurementis performed (72) and the processing cycle is repeated.

In the description of FIG. 2, the detection of lung congestion requiringimmediate attention was the result of a simple volume measurement. Inpractice, however, a slope measurement is preferred to determine when analarm condition is occurring or has occurred, because the variability ofimpedance signals makes it more difficult to achieve accurate thresholddetection by volume measurement.

FIG. 5 is a graph of the device operation using the exemplary detectionalgorithm represented by the flow chart of FIG. 4. The vertical axis 90is conductance, the reciprocal of impedance (1/Z). Therefore, thegreater the lung congestion (i.e., the larger the fluid volume in thepatient's lungs), the lower the value of the term 1/Z. The horizontalaxis 92 represents time. The long-term average of the impedancemeasurement has a characteristic value that filters out the short-termvariations of the measurement. In the Figure, the LT value 96 of curveor slope 94 exhibits a more gradual slope than the ST value 98. Thedifference between the two is used to determine whether an alarmcondition is occurring (LT−ST=V≧threshold).

In addition to the baseline impedance, impedance measurements at thefrequency of 128 Hz can detect impedance changes with every pumpingcycle, to provide indirect information on stroke volume, heart rate, andcardiac output calculated therefrom. Additionally, by adequate low passfiltering, the indirect tidal volume of ventilation can be separatedout, as well as respiratory rate. Typically, ventilation is in a rangefrom 0.2 Hz to 0.8 Hz, while cardiac events are in a range from 1 Hz to3 Hz. Both subsignals, cardiac and ventilation, are used in addition todetermine congestive heart failure indicated by increase in strokevolume, decrease in tidal volume, increase in heart rate, and increasein ventilation rate.

A power saving can be achieved in the device by limiting the impedancemeasurement to fixed periods separated by intervals of no measurement,or even sporadic measurements, rather than performing continuousimpedance measurements.

The impedance measurement electrodes may be used to monitor thepatient's ECG, as well as to obtain the raw data necessary forcalculating absolute impedance and long-and short-term averages ofimpedance. Also, the cardiac- and ventilation-derived impedancephenomena may be correlated to the ECG for better evaluation. Inaddition, a miniaturized accelerometer within the case might givevaluable information with regard to the daily and comparative physicalactivity of the patient.

It is important to consider the factor of where the measurements aretaken as well as the manner of obtaining the measurements. For example,the spacing between the measurement electrodes 14, 16 determines thevolume and area of measurement. By spacing these electrodes at least 4cm apart, the depth of measurement is increased beyond only the tissuein the immediate vicinity of the electrode, to the tissue for whichspecific impedance and impedance changes are sought to be measured,typically to a depth of up to 10 cm of lung tissue. Also, performing themeasurements on the patient's left side rather than the right side, andparticularly on the anterior lateral lower left thorax, enables earlydetection of changes in left ventricular parameters and congestion inthe lung circulatory system, rather than limiting the measurement totissue and liver impedance which is primarily a function of congestionof the right heart. Additionally, at this preferred location forconducting the measurements, the cardiac phenomena and stroke volumedependent impedance changes are more easily detected than on the rightside or the upper left thorax where impedance changes primarily followblood circulation.

Due at least in part to the availability of advanced ultra low-power RF(radio frequency) capabilities, implanted devices such as the CHFmonitor described above, pacemakers, defibrillators and medicinedelivery pumps may communicate in real time or near real time withhealth professionals at a remote location. This communication can befacilitated by means of a repeater—a device for receiving electroniccommunication signals and delivering corresponding amplified ones. Evenmore desirable is a base station which may additionally process datareceived via such electronic communication signals prior to forwardingthe data to a remote location.

Until recently, no globally accepted frequency band has been dedicatedto medical implant device communications. Where communication between animplant and a monitoring system was required, most device manufacturersused short-range systems based on magnetic coupling between coils. Thesesystems required extremely close coupling (less than 10 cm) between themedical device and programmer and offered limited data transfer rates.

This situation changed with the ITU-T Recommendation SA 1346, whichoutlined the shared use of the 402-405 MHz frequency band for a MedicalImplant Communications Service (MICS). This recommendation has beenimplemented in the United States under the Federal CommunicationsCommission (FCC) rules, and in Europe under the EuropeanTelecommunications Standards Institute (ETSI) Standard EN301 839. It isexpected that MICS will become a true global standard within severalyears. Operations rules and technical regulations applicable to MICStransmitters may be found in 47 CFR 95.601-95.673 Subpart E.

The 402-405 MHz frequency band is available for MICS operations on ashared, secondary basis. The FCC determined that, compared to otheravailable frequencies, the 402-405 MHz frequency band best meets thetechnical requirements of the MICS for a number of reasons. The 402-405MHz frequencies have propagation characteristics conducive to thetransmission of radio signals within the human body. In addition,equipment designed to operate in the 402-405 MHz band can fully satisfythe requirements of the MICS with respect to size, power, antennaperformance, and receiver design. Further, the use of the 402-405 MHzband for the MICS is compatible with international frequencyallocations. Finally, the U.S. Federal Communications Commission hasdetermined that the use of the 402-405 MHz frequency band for the MICSdoes not pose a significant risk of interference to other radiooperations in that band.

The 402- to 405-MHz band is well suited for in-body communicationsnetworks, due to signal propagation characteristics in the human body,compatibility with the incumbent users of the band (meteorological aids,such as weather balloons), and its international availability. The MICSstandard allows 10 channels of 300 kHz each and limits the output powerto 25 microwatts.

With rising healthcare costs, an aging population, and a growingacceptance of home-based medical monitoring, the MICS band is spurringadvances in telemedicine. Using MICS, a healthcare provider canestablish a high-speed, longer-range (typically 2 to 20 meters) wirelesslink between an implanted device and a base station. For example, anultra low-power RF transceiver in a CHF monitor can wirelessly sendpatient health and device operating data to a bedside RF transceiver andvice versa. Data can then be forwarded from the base station viatelephone land line, wireless cell phone communication, or the Internetto a doctor.

Advanced ultra low-power RF technology will dramatically improve thequality of life for patients with implanted medical devices. With atwo-way RF link, doctors can remotely monitor the health of patients andwirelessly adjust the performance of the implanted device. This meansfewer unnecessary hospital visits for the patient. Instead, with remotemonitoring the doctor can call the patient in to the hospital when aproblem is detected.

An implantable device such as a CHF monitor may be paired with a basestation or repeater and linked by MICS transceivers. In such a system,data from the monitor may be downloaded to the base station for dataprocessing and analysis using higher performance data processingequipment (which typically has higher power consumption than lowerperformance processors). Moreover, the base station may provide acommunication interface to telecommunications networks such as thePublic Switched Telephone Network (PSTN), computer networks includingthe Internet, and radio-based systems including cellular telephonenetworks, satellite phone systems and paging systems.

Such telecommunications can be used to send data to medicalprofessionals who may use it to make treatment decisions includinghospitalization, pharmaceutical dosage and/or measurement parameters ofthe implanted device. For example, if an increase in congestion isnoted, more frequent measurements of impedance by the implanted devicemay be ordered by a physician via a return communications link.

A representative system is shown schematically in FIG. 6. A device 18 isimplanted in patient P. Device 18 includes a short-range radiotransceiver which utilizes the Medical Implant Communication Service. Acorresponding transceiver in base station 100 receives data from device18, processes and/or stores the data and sends it to a remote locationusing one or more of the Public Switched Telephone Network T, computernetwork I, and radio communications system R. Computer network I may bea local area network (LAN), wide area network (WAN), an intranet or theInternet. Radio communications system R may, in certain embodiments, bea cellular telephone system, the PCS system, a satellite phone system, apager system or a two-way radio link.

In some embodiments, the link between the implanted device 18 and basestation 100 may be a one-way link. For example, implanted device 18 mayhave a MICS transmitter (cf. transceiver) and base station 100 may haveonly a MICS receiver (cf. transceiver).

FIG. 7A is a block diagram of an exemplary base station or repeater 100.A power supply 102 may rectify and covert ac line voltage to dc at thevoltage level(s) required by the various subsystems within the basestation. In some embodiments, power supply 102 may include anuninterruptible power supply (UPS) or battery 102 for operation duringutility power interruptions or to permit brief operation of the basestation at locations without external power. Power supply 102 may use anexternal wall transformer to deliver 9 or 12 volts DC to the system. Aninternal DC-DC converter may be used to step the voltage down to 3.3V(digital supply) and 5V (analog supply & radio(s) supply). An internalDC-DC converter may help to reduce noise (60 Hz line noise, etc). Thiswould help the SNR (Signal to Noise Ratio) of both the wireless dataradio modem, and the medical band radio—improving the range andefficiency of both.

Optional battery 103 can allow device operation for an extended periodof time in the event of power interruption. A 6 Ah @ 6V battery couldprovide several days, if not a week of uninterrupted operation in theevent of power failure. A lightweight battery can be used in a portableembodiment (for example, a 1000-1800 mAh lithium-ion battery couldprovide several days of portable operation).

Processor 104 may be a microprocessor or similar programmed system forimplementing the methods of the system and controlling the varioussubsystems comprising base station 100. As noted above, one particularlysignificant advantage of base station 100 is its ability to use apowerful processor 104 whose electrical power consumption would beprohibitive for use within a battery-operated, energy sensitiveimplanted device such as CHF monitor 18. Microcontroller 104 may be asimple {fraction (8/16)} bit microcontroller.

Attached EEPROM 106 may be used for code/firmware storage, oradditionally used as a temporary storage location for cardiac data inthe even that a network connection is not immediately available.

Attached RAM 108 may be used for code execution/scratchpad, oradditionally used as a data buffer for cardiac data during transmit orreceive.

Certain embodiments of base station 100 may include display or alarms(not shown) for displaying operational data and/or alerting the patientor caregiver of parameters which exceed defined limits.

For short-range communication with implanted device 18, base station orrepeater 100 may include MICS transceiver 118 and antenna 120.Electrically small antennas are generally considered to be those withmajor dimensions less than 0.05 lambda, or in the MICS band, 37 mm. Insome embodiments the corresponding antenna with which the base stationor repeater 100 communicates may be folded within the case of device 18.In other embodiments, the antenna may be outside of the device 18 andencased in epoxy resin or other bio-compatible dielectric material. Inthis way, the usually metal case 24 will not significantly impede RFtransmission to and from the antenna of device 18. In addition, alsomeasuring electrodes for impedance and for EKG might be situated withinthe epoxy header. By way of doing so, the critical feed-through in theotherwise hermetically sealed case might be better protected.

The MICS transceiver 118 enables communication with the implantablemedical device 18. It may operate on a different frequency than the GSMbands to avoid interference with radio modem 114. Interface 118 provideshigh-speed wireless data communication with the implantable device 18,within approximately 6 feet. A stationary base station 100 could beplaced near a bed or other location where the patient could be closeenough for data transmission. Similarly, a portable device could be wornby the patient.

For data communication with remote locations, such as doctor's offices,base station 100 may include network interface 116. One examples ofnetwork interface 116 is an Ethernet Network Interface Card (NIC).Ethernet can be used as an alternative connection to the Internet foruploading patient data, in the event that wireless data service is notavailable or is prohibitively expensive. Ethernet interface 116 can alsobe used for remote management and uploading/upgrading system firmware.An optional modem 117 for data transmission using the public switchedtelephone network may also be incorporated.

An alternative data communication interface for base station 100 isradio modem 114. In certain embodiments, radio modem 114 may be acellular telephone with a modem, or may operated similarly thereto.Radio modem 114 may couple to an antenna 121 which, in some embodiments,may be external to or remote from the main housing of base station 100.The specific design of the antenna depends on the particular band used,but in any event could conform with GSM 900, 850, 1900, or 1880standard. Use of a dedicated GSM/GPRS radio modem 114 can reduce systemcomplexity, as this would require only a power supply and a dataconnection to the system. This reduces overall system complexity.

Data may be transmitted to the Internet using GPRS (General Packet RadioService) over the GSM band. Alternatively, instead of a self-containedradio modem, a quad-band (or tri-band) GSM/GPRS RF (Radio Frequency)transceiver can be used. However only the radio and associatedcomponents are included, so further additional hardware might berequired for baseband processing, etc. This can connect to and switchbetween a greater number of GSM networks, allowing for greater coveragearea (and coverage in more countries).

Alternatively, instead of GPRS/GSM, a different cellular data service,such as X.25 or Cellular Digital Packet Data (CDPD) can be used. Onepreferred embodiment uses a RIM 902M Radio Modem operating in the GSM900 band. For example, RIM's proprietary Radio Access Protocol could beused to communicate with the modem 114 in this example. Alternatively,if a self-contained radio modem from another manufacturer is used, adifferent protocol, such as RS-232, may be used.

In yet other embodiments, if a custom GSM/GPRS RF solution is usedinstead of a self-contained radio modem, a custom interface could bedefined, for example using memory-mapped I/O, or simply the GPIO(General Purpose I/O) pins on the controller to communicate with andcontrol the radio.

SIM Card 110 is a Subscriber Identity Module that identifies aparticular user of a GSM network. SIM card 110 could be keyed to aPatient ID, for example, for billing purposes. Patient ID could beencrypted and sent separately along with patient data.

It will be appreciated by those skilled in the art that base station 100may be in data communication with a plurality of implanted devices. Forexample, base station or repeater 100 could receive pacemaker data froman implanted device of a patient such as the disclosed CHF monitor, apacemaker, a defibrillator, etc. and store such data and transmit itperiodically to a doctor's office. Such a system would permit, forexample, daily monitoring of a patient's condition as opposed tooccasional visits to a doctor's office.

Depending on the digitization rate, device 18 may generate approximately16 to 18 megabytes of data per day. Using the system of the presentinvention, data could be collected by the base station, parsed, analyzedand/or summarized, and periodically sent to a remote facility (such as adoctor's office) on, for example, a quarterly basis. Alternatively,triggering events such as tachycardia or increasing congestion could beused to determine when the base station 100 would open a communicationslink and send data or alarm signals.

Base station 100 could be used with other implanted sensors which couldmonitor, for example, blood glucose level, oxygen saturation,temperature or other metabolic parameters. Such monitoring could beuseful in tracking the cardiovascular fitness not only of patients, butalso soldiers, athletes and others subjected to physical stress or harshenvironments such as special mission pilots or astronauts.

FIG. 7B shows an alternative embodiment of the base station having anintegrated microcontroller which performs several of the function of theseparate function disclosed in FIG. 7A. For clarity, the other systemcomponents shown in FIG. 7A have been omitted.

Implantable device 18 could monitor and record the patient's ECG andother physiological parameters. The implantable device has a limitedpower supply in its on-board battery, and it is desirable to use aslittle power as possible to maximize the life of the device. For thisreason, the implantable device may have internal memory storage capableof buffering or temporarily holding the patient data so it does not needto continuously transmit the patient data. For example, Flash memory orlow-power SRAM can be used for memory storage. Flash memory does notconsume any power once the data has been stored, however the amount ofpower consumed during program and erase can be significant. An SRAMrequires constant power, but the amount of power is small.

The amount of patient data that is collected per 24-hour period is lessthan 20 MB. A simple, power-efficient loss-less data compressionalgorithm may reduce that amount even further, perhaps even in half. Abalance between power used to compress the data and power used totransmit the data is desirable.

As mentioned before, for power conservation reasons, the MICS radio neednot continuously transmit patient data. The patient data may becollected and stored in the memory storage, and subsequently transferredto the device at predetermined intervals. A portable, wearable devicecould use an hourly schedule. A stationary device under normalconditions could upload the data on a daily to weekly schedule.

FIG. 8 depicts an alternative embodiment of the invention, andspecifically shows a device 200 for monitoring CHF implanted in apatient 205. The device 200 has an epoxy header 201 which is on top ofmedical electronics 202 (e.g., FIG. 3) contained in the hermeticallysealed case 200 of the device. The header contains a pair of outerelectrodes 203 and a pair of inner electrodes 204. Those electrodes areconnected through wires 206 which communicate with medical electronic202 through the feedthrough 207. In addition, an antenna 208 isincorporated in the epoxy header for communicating signals in themedical implant communications service bands. An antenna 208 having alength of ¼ lambda may be used to transmit signals effectively. Throughradio frequency radiation 209, the device communicates with the basestation or repeater 210 (similar to base station 100 of FIG. 7A forexample) in the proximity of the implant patient 205. The base station210, which receives the signals from the implant device 200, cantransfer and/or amplify the signals, which in turn can be easilycommunicated through a wireless local network or a personal area network211 to the interface of a computer 212, preferably also in the proximityof the patient. Further connections through Internet lines 213 occurwith a data handing and coordinating center 215 for further storage andanalysis of this data. Instead of a repeater 210, communication pathway211 and communication computer 212, a single unit 214 as shown in FIGS.7A and 7B is feasible.

The data handling and coordination center 215 primarily receives thedata either in a continuous manner, in a temporary intermittent manner,or in a predetermined activated manner as dictated by the implant device200. Signals can be received either as live or stored data, or aspreprocessed data, or as data that fulfill certain selection criteria(such as an alarm condition). The data transfer occurs intermittently orcontinuously. The transfer of the stored data for one day, for example,can occur at certain fixed time periods (e.g., at night) or when thepatient is in the proximity of the local repeater. This proximity isdefined dependent on the power output of the device through the medicalimplant service bandwidth and preferably is kept at a low level toconserve battery life, battery power, and to extend the life of theimplant device.

Also, to preserve energy and optimize the capacity of all links involvedin the data processing, data is preferably only sent if they fulfillcertain criteria. The criteria can be incorporated in the logic orprogramming of the circuitry 202 of the implant device 200 or withinsimilar logic or program of the base station 210. Despite such criteria,data indicative of an emergency condition can be made to transfer on apriority basis, such as immediately, if sensor data from the device 200indicates a life threatening condition such as tachycardia or anabnormal slow rate, which in turn could prompt immediate intervention bya physician and/or transfer of the patient to an emergency room. Theemergency condition can be accompanied by an alert 217, which can becommunicated to both the patient (via links 213, 212, 211, 210, and209), and to a local patient care physician center 216. The alert may bemanifested to the patient from a audible sound, vibration, or some otherphysical indicator emanating from the device 200. Either way, aphysician at the center 216 and/or the patient can then establishcommunication with each other through traditional means (Internet,phone, e-mail, direct physical presence, etc.). As communication withthe device is two-way, the doctor may also request additional data fromthe device, and/or can program the device 200 to perhaps better assistthe health of the patient.

Because electrodes 203 and 204 are situated outside the hermeticallysealed case in a nonmetallic header 201, preferably a polymer of epoxyresin, the feedthrough 207, which is the most sensitive point in thehostile environment of the human body, can be protected. Moreover, aswell as providing mechanical shielding for the feedthrough 207, theheader 201 provides electrical shielding. Moreover, the header 201preferably contains the MICS-band antenna 208, which will suffer lessattenuation than were the antenna disposed within the hermeticallysealed metallic case 200 of the device. As shown, the same electronicfeedthrough 207 is used for both the antenna 208 and the electrodes 203,204, but different feedthroughs may also be used.

For data storage, the device electronics 202 can digitize the dataaccordingly to its signal characteristics. For example, the EKG can bedigitized with a sampling frequency of 100 Hz. If this is done, theresulting quantity for one day would roughly constitute 8 to 9megabytes. An activity signal of a miniaturized accelerometer which isalso incorporated in the hermetically sealed device and preferablysituated on hybrid electronic circuitry 202 can be digitized at a muchslower rate in a range of 10 Hz, perhaps amounting to less than 1megabytes of data per day. For the impedance measurements, as describedin the referenced and related applications, another 8 megabytes could berequired bringing the daily data amount to roughly 16 to 20 megabytes.Modem storage memories incorporatable into the device 200 can easilyhandle such data, and a memory of 256 mega bits could handle the datafor nearly 2 weeks. In short, data for a whole host of patientparameters can be stored and periodically transferred, say every otherday or week, unless built-in data handling and analysis triggers anearlier transmission of the data (such as during an emergencycondition).

FIG. 9 illustrates another embodiment of the present invention. In thiscase, the implant device 200 is comparable to the device described inFIG. 8. However, in this embodiment, communication occurs with a cellphone 221 which acts as a repeater/base station programmed withappropriate logic 220 to perform the function of the base station asdiscussed above. Such logic 220 can appear within the phone 221 itself,or in a traditional phone socket or cradle. Cell phone 221 communicatesvia an RF interface with the implant device 200, and furthercommunicates via an RF telephone link 222 to, for example, the Internet223, which can comprise one network intervening between the phone 221and the coordination center 215, where data is stored and/or analyzed.(one skilled in the art will realize that other communication networksin addition to the Internet would logically be used, but are not shown).Alerts indicative of emergency conditions can be sent to the patient viathe Internet 223 either to the cell phone, or through wireless cellphone communication from the patient care center 216 to cell phone 221.Further communication of the alert to the patient can then becommunicated through radio frequency link 209 to the device 200. On theother hand, the local patent care physician center 216 can alert thepatient through communication link 217, which may be direct access,email, phone calls or physical presence of a person to assist thepatient and resolve the current medical situation.

FIG. 10 illustrates an advanced method of information technology andhandling. The implant device 200 communicates through the mobile implantcommunication service band through links as described previously eitherthrough wireless, telephone, Internet, or land line telephone with thedata handling and coordinating center 215. In this center 215,evaluation of the data from the device 200 may be accomplished asbefore, but, in addition, other patient specific data like patienthistory, current medication, age, and other patient relevant informationis assessed, as pulled from database 230. Furthermore, analysis can befurther assisted via data pulled from a library database 231 of currentarticles, from a medicine guidelines database containing recommendationsfor certain patient conditions, and from a drugs and adverse effectdatabase 234. This culmination of data (current patient data from device200, historical patient data, etc.), can be used at center 215 toprovide, in automated or semi-automated fashion, the best course ofaction or recommendation for a particular patient. This recommendationcan be transmitted to the local patient care physician center 216 toallow a better evaluation of what might be done with the patient andwhat kind of measures could be given. It is up to the physician tocommunicate this kind of decision and recommendation to the patientincluding any action such as taking diuretics, new medications, betablockers, antiarrhythmias, or the recommendation for implant of a brady-or tachyarrhythmia device.

Implanted devices 200 may be programmed via the base station 210 and itsassociated data link(s). Such programming could replace the magneticwand programming of the prior art which typically must be performed in ahealthcare facility or doctor's office.

By using the system of the present invention, implanted devices may bereduced in physical size. Implanted devices used in conjunction with thebase station provide the benefit for allowing store and intermittenttransfer of data. Sending data in short bursts not only conserves power(permitting smaller batteries to be used in the devices 200), but alsoreduces the potential time window for interference and provides moreforgiving power supply requirements. This is important for implantsystems, which frequently use batteries with high impedance. Thisapproach also makes the use of a very high data transmission rateattractive for intermittent telemetry applications, such as inpacemakers, as a large capacitor can have its charge mortgaged for theperiod of the radio transmission, and then recharged at a lower rate.Another fact that points in favor of a high data rate is that thetransmission will occur during a shorter time period, making it possiblefor more users to share the same radio channel.

Although a presently contemplated best mode, preferred embodiment andmethod of practicing the invention have been described in thisspecification, it will be apparent to those skilled in the art from aconsideration of the foregoing description that variations andmodifications of the disclosed embodiments and methods may be madewithout departing from the spirit and scope of the invention. It istherefore intended that the invention shall be limited only to theextent required by the appended claims and the rules and principles ofapplicable law.

1. A system for detecting and monitoring congestive heart failure in apatient, comprising: a body-implantable device comprising a circuitmodule having surface electrodes on the device arranged and adapted,when the device is implanted, for exposure to tissue in a portion of thepatient's body generally occupied by the lungs, to perform ongoingmeasurements of impedance of said body portion; a radio-frequencytransceiver within the body-implantable device in data communicationwith the circuit module for transmitting the measurements of impedance;and, a base station comprising a radio-frequency transceiver forreceiving data from the body-implantable device and sending instructionsto the body-implantable device, and an interface for sending datareceived from the body-implantable device to a remote location and forreceiving instructions from a remote location.
 2. The system of claim 1,wherein the telecommunications interface comprises a telephone modem. 3.The system of claim 1, wherein the telecommunications interfacecomprises a computer network interface.
 4. The system of claim 3,wherein the computer network interface is an Ethernet interface.
 5. Thesystem of claim 1, wherein the telecommunications interface comprises aradio transceiver.
 6. The system of claim 1, wherein thetelecommunications interface comprises a modem and a cellular telephone.7. The system of claim 1, wherein the data comprises digitized impedancevalues.
 8. The system of claim 1, wherein the data representsinformation related to the performance of the body-implantable device.9. The system of claim 1, wherein the instructions determine theinterval between measurements.
 10. The system of claim 1, wherein theinstructions set a threshold value for a patient-sensed alarm.
 11. Thesystem of claim 1, wherein the radio frequency transceivers operate at afrequency between 402 MHz and 405 MHz.
 12. The system of claim 1,wherein said body-implantable medical device is shaped to be implantedat a site on the left lower anterior lateral hemithorax of the patient'sbody.
 13. A system for monitoring the condition of a patient sufferingfrom congestive heart failure, comprising: a body-implantable medicaldevice having circuitry including plural surface electrodes on thedevice for measuring impedance between a measurement pair of saidelectrodes from a predetermined electrical parameter injected in acircuit path between an excitation pair of said electrodes, such thatwhen said device is implanted at a site where said circuit path includesthe patient's heart and lungs said impedance measurement is indicativeof lung congestion; a radio transmitter within the body-implantabledevice in data communication with the circuitry for measuring impedancesaid transmitter adapted to transmit data representing the measuredimpedance; and, a base station comprising a radio receiver for receivingdata from the body-implantable medical device and an interface forsending the data to a remote location.
 14. The system of claim 13,wherein the telecommunications interface in the base station comprises atelephone modem.
 15. The system of claim 13, wherein thetelecommunications interface in the base station comprises a cellulartelephone and a modem.
 16. The system of claim 13, wherein thetelecommunications interface in the base station comprises a two-wayradio.
 17. A device-implemented method of detecting and monitoringcongestive heart failure in a patient, comprising: performing ongoingmeasurements of impedance of a portion of the patient's body generallyoccupied by the lungs; transmitting said measurements of impedance to abase station using a radio transmitter; and, sending data relating tosaid measurements of impedance from the base station to a remotelocation via a telecommunications network.
 18. The device-implementedmethod of claim 17, including injecting said electrical current in theform of a biphasic pulse wave.
 19. The device-implemented method ofclaim 17, including performing said impedance measurements outside thepatient's thoracic cage.
 20. The device-implemented method of claim 17,including performing said impedance measurements using electrodes of thedevice outside the patient's vascular system.
 21. The device-implementedmethod of claim 17, including using said surface electrodes of thedevice additionally to monitor the patient's ECG.
 22. Thedevice-implemented method of claim 17, including performing saidimpedance measurements with the device implanted on the lower leftanterior lateral hemithorax.
 23. The device-implemented method of claim17, wherein said body portion further encompasses the patient's heart,including performing said impedance measurements by means of a signalinjected into said body portion from the device and retrieved as asignal subdivided into a cardiac portion, a pulmonary portion, and atotal impedance portion.
 24. A method for communicating with animplantable device, comprising: transmitting data from the implantabledevice via the Medical Implant Communication Service band to a basestation; and transmitting modifications to the implantable device fromthe base station via the Medical Implant Communication Service band tothe implantable device, whereby the modifications are implemented at theimplantable device.
 25. The method of claim 24, wherein the modificationcomprise modifications to settings, function, characteristics orparameters of the implantable device.
 26. The method of claim 24, wherethe base station further communicates the data and/or modification to anetwork.
 27. The method of claim 26, wherein the network comprises atelephone land line network, a wireless telephone network, and/or theInternet.
 28. The method of claim 24, wherein the base station comprisesa wireless telephone.
 29. The method of claim 24, wherein theimplantable device comprises a congestive heart failure monitoringdevice, a cardiac pacemaker, a defibrillator, a neurostimulator, amuscle stimulator, a gastric stimulator, or a diagnostic implantabledevice for monitoring CO₂, blood pressure, oxygen, glucose, ventilation,heart rate, activity, posture, hormones, cytokines, or neurofunctions.30. The method of claim 24, wherein the base station is proximate to theimplantable device.
 31. The method of claim 24, wherein the implantabledevice is implanted in the chest of a patient.
 32. The method of claim24, wherein the data is indicative of a patient's health, and whereinthe modifications are achieved through an assessment of the data at thebase station.
 33. A base station for communicating with an implantabledevice, wherein the base station is capable of bi-directionalcommunication with the implanatable device via the Medical ImplantCommunication Service band when the implantable device is in proximityto the base station, and wherein the base can both control theimplantable device, and receive data from the implantable device. 34.The base station of claim 33, wherein the base station can control theimplantable device by providing instructions to change the implantabledevice's settings, functions, characteristics or parameters.
 35. Thebase station of claim 33, where the base station is further capable ofcommunicating the data to a network.
 36. The base station of claim 35,wherein the network comprises a telephone land line network, a wirelesstelephone network, and/or the Internet.
 37. The base station of claim33, wherein the base station comprises a wireless telephone.
 38. Thebase station of claim 33, wherein the received data comprises datareceived from a congestive heart failure monitoring device, a cardiacpacemaker, a defibrillator, a neurostimulator, a muscle stimulator, agastric stimulator, or a diagnostic implantable device for monitoringCO₂, blood pressure, oxygen, glucose, ventilation, heart rate, activity,posture, hormones, cytokines, or neurofunctions.
 39. The base station ofclaim 33, wherein the data is indicative of a patient's health, andwherein controlling the implantable device occurs as a result ofanalysis of the data by the base station.
 40. An implantable device,comprising: a metallic can containing electronics; two pairs ofelectrodes coupled to the electronics, a first pair for providingelectrical energy to a portion of a patient's body, and a second pairfor detecting a health parameter of patient's body in response to theelectrical energy; an antenna coupled to the electronics forbroadcasting data indicative of the health parameter to outside of thepatient's body, wherein the pairs of electrodes and the antenna areencased in a polymer header coupled to the can.
 41. The device of claim40, wherein the electrode pairs and the antenna are coupled to theelectronics via a feedthrough between the can and the header.
 42. Thedevice of claim 40, wherein the polymer header comprises a resin. 43.The device of claim 40, wherein the antenna further receives data fromoutside the patient to program the device.
 44. The device of claim 40,wherein the antenna communicates via the Medical Implant CommunicationService band.
 45. The device of claim 40, wherein the electronicscomprises a memory for storing the data indicative of the healthparameter.
 46. The device of claim 45, wherein the electronics isprogrammed to broadcast the data indicative of the health parameter tooutside of the patient's body from the memory at intermittent intervals.47. The device of claim 45, wherein the health parameter comprisesfluidic impedance.
 48. A method for communicating with an implantabledevice, comprising: transmitting data from the implantable device viathe Medical Implant Communication Service band to a base station inproximity to the implantable device; and further transmitting the datafrom the base station to a health care provider via a network.
 49. Themethod of claim 48, wherein the network comprises a telephone land linenetwork, a wireless telephone network, and/or the Internet.
 50. Themethod of claim 48, wherein the base station comprises a wirelesstelephone.
 51. The method of claim 48, wherein the implantable devicecomprises a congestive heart failure monitoring device, a cardiacpacemaker, a defibrillator, a neurostimulator, a muscle stimulator, agastric stimulator, or a diagnostic implantable device for monitoringCO₂, blood pressure, oxygen, glucose, ventilation, heart rate, activity,posture, hormones, cytokines, or neurofunctions.
 52. The method of claim48, wherein the implantable device is implanted in the chest of apatient.
 53. The method of claim 48, wherein the base station amplifiesthe data before the further transmission.
 54. The method of claim 48,wherein the base station analyzes the data before the furthertransmission.
 55. The method of claim 48, wherein the base station canfurther send communications to the implantable device.